Steam engines require a “blowout valve,” really a safety valve that will blow off steam (that’s where we got the famous phrase) before a serious problem builds up in the explosive steam engine. You don’t often get to see the safety valve in action on the Liberty Belle, but we saw it last week.
It’s the front, right (i.e., starboard bow) side of the boat where the valve is located. It makes a startlingly loud hissing sound when it happens. In fact, it sounds like something is wrong.
These photos were taken as the boat rounded Big Thunder, and we later learned the blowoff was initiated on purpose by a mechanic traveling on board. So in this instance, it was not a case of “problem narrowly averted” so much as “testing that the safety valve does its job.” Still, they are neat images to see!